1. cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0:1
2. In /etc/sysconfig/network-scripts/ifcfg-eth0:1 change DEVICE=eth0 to DEVICE=eth0:1
3. In /etc/sysconfig/network-scripts/ifcfg-eth0:1 modify IPADDR= to match the additional TCP/IP address you wish to use.
4. Start the secondary interface:
ifup eth0:1